package org.duiduo.utils;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

/**
 * AES加密解密工具类
 */
public class AESUtil {

    private AESUtil() {
        throw new AssertionError();
    }
      
	// 加密  
    public static String Encrypt(String sSrc, String sKey) throws Exception {  
        if (sKey == null) {  
            System.out.print("Key为空null");  
            return null;  
        }  
        // 判断Key是否为16位  
        if (sKey.length() != 16) {  
            System.out.print("Key长度不是16位");  
            return null;  
        }  
        byte[] raw = sKey.getBytes("utf-8");  
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");  
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");//"算法/模式/补码方式"  
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);  
        byte[] encrypted = cipher.doFinal(sSrc.getBytes("utf-8"));  
        return parseByte2HexStr(encrypted);//此处使用BASE64做转码功能，同时能起到2次加密的作用。  
    }  
   
    // 解密  
    public static String Decrypt(String sSrc, String sKey) throws Exception {  
        try {  
            // 判断Key是否正确  
            if (sKey == null) {  
                System.out.print("Key为空null");  
                return null;  
            }  
            // 判断Key是否为16位  
            if (sKey.length() != 16) {  
                System.out.print("Key长度不是16位");  
                return null;  
            }  
            byte[] raw = sKey.getBytes("utf-8");  
            SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");  
            Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");  
            cipher.init(Cipher.DECRYPT_MODE, skeySpec);  
            byte[] encrypted1 = parseHexStr2Byte(sSrc);//先用base64解密  
            try {  
                byte[] original = cipher.doFinal(encrypted1);  
                String originalString = new String(original,"utf-8");  
                return originalString;  
            } catch (Exception e) {  
                System.out.println(e.toString());  
                return null;  
            }  
        } catch (Exception ex) {  
            System.out.println(ex.toString());  
            return null;  
        }  
    }  
    
    
    /**
     * 将二进制转换成16进制
     * 
     * @param buf
     * @return
     */
    public static String parseByte2HexStr(byte buf[]) {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < buf.length; i++) {
            String hex = Integer.toHexString(buf[i] & 0xFF);
            if (hex.length() == 1) {
                hex = '0' + hex;
            }
            sb.append(hex.toUpperCase());
        }
        return sb.toString();
    }

    /**
     * 将16进制转换为二进制
     * 
     * @param hexStr
     * @return
     */
    public static byte[] parseHexStr2Byte(String hexStr) {
        if (hexStr.length() < 1)
            return null;
        byte[] result = new byte[hexStr.length() / 2];
        for (int i = 0; i < hexStr.length() / 2; i++) {
            int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);
            int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2), 16);
            result[i] = (byte) (high * 16 + low);
        }
        return result;
    }
   
    public static void main(String[] args) throws Exception {  
        /* 
         * 此处使用AES-128-ECB加密模式，key需要为16位。 
         */  
        String cKey = "1qaz2wsx3edc4rfv";  
        // 需要加密的字串  
        String cSrc = "small_wl_cd";
        System.out.println(cSrc);  
        // 加密  
        String enString = AESUtil.Encrypt(cSrc, cKey);  
        System.out.println("加密后的字串是：" + enString);  
   
        // 解密  
        String DeString = AESUtil.Decrypt(enString, cKey);  
        System.out.println("解密后的字串是：" + DeString);  
    } 
}